1. Field of the Invention
The present disclosure relates to a semiconductor device.
2. Description of the Related Art
In a semiconductor device such as a semiconductor laser element, characteristics are deteriorated in accordance with electrification. For example, it is known that catastrophic optical damage (COD) occurs on an edge in an edge emission type laser element. As a technology for preventing COD, a window structure for suppressing absorption of laser light on an edge is known (refer to Japanese Laid-open Patent Publication No. 2012-146996).
In deterioration of characteristics of a semiconductor device, deterioration due to deterioration of an edge thereof has received an attention. Therefore, countermeasures to the deterioration of characteristics of a semiconductor element have been developed around a technology to protect an edge of a semiconductor device.
However, according to studies by the present inventors, defects to cause deterioration of characteristics may be generated not only on an edge of a semiconductor device but also in a bulk of a semiconductor crystal in accordance with higher output or higher breakdown voltage of the semiconductor device. For example, the present inventors have confirmed that a dislocation loop not caused by an edge is generated and the dislocation loop is grown in a bulk in an active layer of a semiconductor laser element or in the vicinity thereof. This tendency is significant particularly in a high output element having an optical power of about several tens W or more at one chip.
There is a need for a semiconductor device suppressing generation of defects in a bulk of a semiconductor crystal and having less variation of characteristics.